Preheat oven to 400 degrees
In a large skillet melt butter over medium high heat
Add onion and saute until translucent then add carrots and peas and cook until carrots get a little tender
Sprinkle flour over vegetables and cook for 1-2 minutes
Gradually whisk in liquid and Better Than Boullion, and bring to a slow boil
Simmer gently over medium heat until sauce begins to thicken, about 5 minutes
Add chicken and thyme and season with salt and pepper to taste
Pour chicken mixture into prepared casserole dish
Mix biscuit mix according to package directions and dollop on top of chicken mixture
Bake for 25-30 minutes until top is browned and sides are bubbly